Gareth Mitchell: This is the official podcast of Imperial College, London. Hello everyone. I'm Gareth Mitchell of the BBC's Digital Planet and Imperial's Science Communication Group. Welcome along to this, our August edition. Lots in store for you this time, including how to banish food poverty in Africa. A leading agricultural ecologist and former government advisor returns to Imperial to do his bit. More on that in just a moment. But also today, shedding light on dark energy, or at least trying to. A physicist squares up to the astronomers and tells them that it's time for a new model.

Subir Sarkar: The astronomers see that three-quarters of the universe is dominated by a mysterious fluid called dark energy and I'm here to argue that this dark energy does not in fact exist. That it is a figment of the astronomers' imagination. They're interpreting the detail in an over-simplified model of the universe. And I just wish that astronomers would stop pursuing this type of model and do the hard work of checking their approximations.

GM: Some pretty forthright words there. Who says science is always a genteel activity. And from the theoretical to the very practical. A word with one of our transport people who is working on the human side of making aviation even safer.

Arnab Majumdar: Research here at the Centre for Transport Studies has looked at how air traffic controllers recover when the equipment fails. And you find that communications and teamwork are such essential elements in a very successful recovery for air traffic controllers should the radar screen freeze and the position of aircraft be unknown to them.

GM: And also, grafting new bone tissue in patients where original bone has been lost through disease. A technique for ensuring better implants. That's in our news section right here on the Imperial College podcast.

First, though, how the Philanthropic Trust of one of the world's richest couples is spending millions to help some of the world's poorest people and bringing in some of Imperial's best people to help. The Bill and Melinda Gates Foundation has just provided a new grant devoted to European support for agriculture in Africa. The focal point of all the effort will be Imperial and the job is to establish who's doing what across Europe in terms of agriculture in development and to find out from Africa what it wants from Europe. It's all about attacking food poverty in Africa and improving agriculture in the region in the face of challenges like climate change, disease and conflict.

Leading the initiative is a big job which is why it needs a big person. Step forward Professor Sir Gordon Conway. He's one of the world's most prominent agricultural ecologists. He's just ended a stint as chief scientist at the UK's Department for International Development and has also been president of the Rockefeller Foundation in the United States and Britain's Royal Geographical Society. He's also had a long association with Imperial. He joined the College for the first time back in the 1970s. Well, now he's back again leading that Gates Foundation grant. So sitting in his new office surrounded by boxes full of books that still need to be unpacked and put on the shelves, Gordon Conway told me more about his new role and what he's setting out to achieve.

Gordon Conway: In a sense you have to start with the start. And the start is right now the food crisis that we've experienced in the last couple of years. Food prices went way through the roof and as a result a 100 million more people are chronically hungry in Africa. That's a 100 million on top of that 850 million who were already hungry around the world. So we've got massive hunger throughout Africa. So the question is how do you do something about that? What does it take? And we know it's complicated. We know it's partly about science and technology. It's about new varieties and new fertilisers and new irrigation systems and so on. It's also partly about delivery systems: getting the seed and the fertiliser out to farmers. And it's also partly about having good government institutions and good economic policies. So it's all of those things together. It's also, I should say, about trade as well. Because it's not just about hunger it's also about farmers in Africa being able to sell their produce overseas and particularly to sell it to Europe, of course. So it's all those different factors.

GM: And is that why you and the Bill and Melinda Gates Foundation are so keen on the European angle; because different European states have different things they can bring to the party? So, for instance, some I would imagine are particularly hot on irrigation. Others are very into genetically modified organisms. So is it really just trying to draw out the best of what the individual European states have?

GC: Yes, I think that's true. I think different countries; the Dutch, of course, are very good on water control and irrigation systems. We've got some very good plant breeding in Britain at various institutions. In France they've got a lot of experience of working on farmer organisations. I was in France last week listening to that. And of course there's the general issue that the French working in Francophone Africa have got all kinds of experience and lots of successes. And the British and some other countries working in Anglophone Africa have got also their own experiences and successes. But they don't talk to each other very much yet.

GM: Here's a tough question for you. What's the biggest challenge that you face in all this? You know, in achieving this bigger picture of making Africa, I suppose, self-sufficient or as self-sufficient as it can be in terms of agriculture. Because you're up against, obviously, disease, crushing poverty, lack of education, corruption and all these things. Out of them what's the one big problem that springs to mind in all this?

GC: Well, we all know what the basic prerequisite is for agricultural development and for development generally, and this is good governance and good macroeconomic policies. I mean, that's well established. And countries that have got that move ahead very well. Ghana, for example, is a good example of a country with good governance, good macroeconomic policies and its agricultural development has gone extremely well. So we know the framework for it. But when you come down to the specifics the problem is it various from place to place. There's no blueprint. You can't produce a blueprint for Ghana and apply it to Uganda or you can't produce a blueprint for Burkina Faso and apply it to Malawi. Each place has a set of problems or obstacles to agricultural development. There may be lack of infrastructure or lack of private markets or lack of inputs or lack of market information, lack of new varieties and so on and so forth. The list is about 20 to 30 big obstacles but they vary from place to place and some are more important in some places than in others. Rural roads may be very important in one country; appropriate varieties may be very important in another. So you have to do those diagnostics. And then you have to get people together, the donors together, to agree with the government that that is what's important and to start to invest their money in helping to build up solutions to the problems overcoming the obstacles.

GM: One question that I'm sure you always get asked: genetically modified organisms. GM crops. And especially when we've already agreed that science is going to be part of the solution for Africa. So what role do you see GMOs playing?

GC: Well, one part of the solution to agricultural development in Africa is producing new varieties, new crop varieties. We need new crop varieties that will increase yields. W e need new crop varie ties that will improve the quality of the food that comes from those crops. In other words, they need to have micro-nutrients, vitamins, in them, for example. We need new crop varieties that will resist t he terrible pests and diseases in Africa. One needs to realise there are some appalling pes ts and diseases in Africa. And then we also need new crop varieties that will withstand climate change and in particular drought. Most of Africa is going to be more drought-ridden in the future. We know that. So you need crop varieties that will withstand drought. So we need new varieties. And the question is how do you produce those new varieties. Now, in many cases you can produce it through conventional means. In other cases you can use molecular techniques such as marker aided selection, which is a technique which allows you to speed up the breeding process. And you can also use genetic modification. It's one of the tools that will help you achieve those different results. It's not ‘the' answer but it is one technology that we need to use alongside all the other technologies where it's the most appropriate. And so that's where they sit.

GM: Now, having done a bit of homework reading around about you to prepare for this interview one description comes to many of these articles that you're an optimist, basically. Does that mean that for you Africa is an enormous opportunity? It's not a continent full of problems, as such, there's just so much potential there and to create agriculture in a way that is fair, that is equitable, that is sustainable and all those other important things?

GC: Well, it's interesting that. People often ask me why am I an optimist and why haven't I retired long ago and taken up golf or whatever. I think actually optimism is partly genetically inherited and so I think that's important. But it's also that I've spent a lot of my life in development. I mean, I remember I was working in Indonesia in the 1960s. I was in Indonesia very soon after the massive uprising and the slaughter of hundreds of thousands of Indonesians. I mean, it was a terrible situation. And I've worked a lot in Thailand and I was in Thailand when there were really serious issues. And yet you look at both those countries, they're not perfect, they've got problems like we've got problems in Britain, but they've developed. I've seen development. I mean, these are places I've seen develop in my lifetime. There are examples out there. And there are examples in Africa of countries that are moving along that pathway. I've talked about Ghana already and that's a good example. Tanzania is doing well. Even Malawi is beginning to do quite well at the moment. Uganda has done very well in the past. We know in many circumstances in many conditions what to do. One of the reasons for my optimism today is that there are many really first class African leaders in their 40s and 50s in agriculture who've got really very clear ideas about how to get agriculture moving in Africa.

GM: And for you in many ways this is full circle. Your career started at Imperial, or the very early stages of your career were at Imperial in the 1970s. You've been all over the world. You've been a chief scientific advisor at the Department for International Development. And now here you are after all that, after all these adventures, all these challenges, back here at Imperial College. So how does that feel?

GC: It feels great. It's wonderful. I first joined Imperial College in 1970 and in 1976 I set up the Centre for Environmental Technology here and we were housed in 38 Princes Gardens. And here I am back in Princes Gardens at number 15. It's a wonderful kind of circle, I think. I'm here at Imperial because it's a great university. I think under the leadership of Roy Anderson we've got a great new future ahead of us. Imperial is tremendous because of its commitment to science and technology. Where I think I can add and where other people who are coming to Imperial at the moment, people like Peter Piot who is in the same building downstairs who has created the Institute for Global Health and came from UN Aids. What we can do is to make the scientists and technologists who do such brilliant work at Imperial better aware of the policy implications in components of what they do. That's what I hope I can bring to Imperial College. But I know that I can take a lot from Imperial College because of the tremendous work that goes on here.

GM: Sir Gordon Conway, Professor of International Development, spending four days a week here at Imperial on agriculture in Africa that leaves him a day a week to help China achieve a low carbon future. Indeed, Professor Conway isn't someone who shies away from a challenge. In fact I'll have more from him in next month's podcast including his work in China and his fears for children elsewhere in the world who can go an entire weekend without eating a decent meal. So where's that then? Well, shockingly right in the heart of England. Come back next month for that. But still to come in this edition, debate over dark energy and how to make flying even safer. That's all after some headlines from around the College.

Headlines from around the College

GM: How to treat people in terrible pain having lost bone through cancer or an accident perhaps? Well, patch it up with bone-like material. But matching the implant with a patient's existing tissue isn't easy. Which is why there's excitement this month as Imperial researchers reveal a highly accurate method for distinguishing crucial differences between varying bone-like materials right down to their chemical structure. The idea is to get the best out of stem cell base techniques where new bone is grown from precursor cells. A team in Imperial's Department of Materials and the Institute of Biomedical Engineering has pioneered a new technique based on microscopy, spectroscopy and some pretty comprehensive statistical analysis for telling different types of bone apart. To prove its effectiveness the researchers compared material grown from three different types of mouse stem cells. Whilst they all appeared superficially similar two of them emerged as viable materials but the technique revealed that the mineral composition of one was too simple and a relatively poor form of bone. Armed with this much more accurate way of classifying different structures the researchers say it should help doctors more successfully implant materials into patients.

And Imperial College has a plan to ease the shortage of science teachers in State schools. It involves training actual scientists up as teachers and then fast-tracking them into the classroom. That's the idea behind the Inspire programme which offers specialist teacher training to science postgraduates. The scheme include plenty of on-the-job training in school and pays the students a tax-free bursary during the nine month course. Seven participants have just received their PGC certificates including Elizabeth Tate. She's always fancied teaching a s a career and after her PhD she realised that she preferred lecturing to research. For her one of the highlights has been the opportunity to give school students a first-hand account of a life in science.

Elizabeth Tate: We went to all the schools who are involved in the programme and did a talk on our research. So we went to different classes and talked to them about research after university, after a normal undergraduate degree.

GM: Newly qualified teacher Elizabeth Tate ending this month's news roundup. Well, perhaps you're a postgraduate tempted to get into teaching yourself and if you want to find out more about Inspire then that story is up on our Press Office website. For that and more just go to

Now, one of the delights of working at a big university like Imperial is sifting through your emails and happening on a subject line lik e "invite to the fate of the universe". I s uspect there are rela t ively few workplaces where the day-to-day menu of bits and pieces going on include events devoted to asking big questions like where we all come from and what are universe is made of. And that email was an invitation from our astrophysics group to a discussion over whether dark energy exists or not. On one side, popular belief among astronomers an d cosmologists that this hypothesised dark energy is w hat's driving the universe to expand a t an ever increasing rate. And on the other side, the charge from some physicists that dark energy is really just a made up fudge to account for discrepancies between theory and observation. And that's just not good enough, they say. It's a debate sufficiently highly charged to fill a whole lecture theatre on a summer's evening and to lure in our Imperial podcast reporter and Science Media Production MSc student Elizabeth Hawk. There was no chance of consensus breaking out but it was an ideal opportunity to hear arguments on either side from two big hitters in astronomy and physics. As attendees filed into the lecture theatre Elizabeth caught up with two of the organisers, Professor Andrew Jaffe and, first, Dr Roberto Trotter.

Roberto Trotter: Dark energy is one of the main puzzles of physics today. It's something which is out there in space and across the universe and we think actually makes up about 70 per cent of the known universe. Actually I should say the unknown universe. And so dark energy is one of the biggest mysteries. And one of the key properties of dark energy is that it acts as a sort of anti-gravity which means it seems to be pushing the universe apart and ripping the cosmos apart. But actually some people actually doubt that dark energy really exists. And this is the big question that we're going to ask tonight. Our speakers will debate whether dark energy really exists or not.

Elizabeth Hawk: So Professor Jaffe that's probably where I should bring you in. What's your position on this?

Andrew Jaffe: Well, I guess unfortunately I have to take the position that dark energy does indeed seem to exist. I am pretty sure observationally that dark energy fits the data very well but, as people who attend tonight will hear, what we don't know is what the dark energy actually is. And the real problem there is that to the extent that we have any idea what the dark energy might be we are off by a number that is one followed by something like between 60 and 120 zeros. So we're very, very off. Our theory is very, very wrong. And this is what gives some people, like my interlocutor, pause and makes them think that perhaps it doesn't really exist.

EH: Supposing that dark energy does exist why is it important to know about it?

AJ: Well, it makes up about 70 per cent of the energy of the universe. So it's most of what's out there and so I think just by that very fact alone it behoves us to understand. Even more importantly, or perhaps more importantly, depending on exactly what makes it up it also controls the ultimate fate of the universe or at least our part of the universe. If it is, in its simplest form it implies that the universe will become a very cold and desolate and very boring place and that we're actually very lucky to be a species exploring the cosmos now. Because if we were to come a couple of billon or tens of billon years later then in fact we would find the universe very desolate and we'd only be able to see our galaxy, if that, and nothing much else at all. So it's a much more interesting universe that we live in now because of dark energy.

LH: You were saying that there's obviously something very wrong with the current theory even though you think that dark energy does exist. So what is the supporting evidence that underpins your position?

AJ: Well, dark energy's main property is that it makes the universe's expansion accelerate over time. So we've known since the 30s that the universe is expanding over time but only in the last 10 or 15 years have we had conclusive evidence that the universe's expansion is getting faster and faster and faster. And it turns out that no normal matter can make the universe accelerate in its expansion. So the main observational technique that we have is just to look at things and see that they are moving away faster than we might have otherwise thought.

EH: Just found a quiet corner so let's have a few words with Professor Subir Sarkar, who is going to be Professor Jaffe's opponent in the debate, and he's from the University of Oxford. So can you tell me a bit about your position on dark energy?

Subir Sarkar: Well, it's a great honour to be invited here to be subjected to the conventional point of view from Professor Andrew Jaffe, who is in the Department of Astrophysics here. And he represents, I would say, over 90 per cent of all practising cosmologists who believe that we have found a so called standard model of the universe. And the puzzling thing about this standard model is that it might make sense to astronomers but it makes no sense at all to physicists. Nonetheless physicists are very concerned about it because the astronomers say that three-quarters of the universe is dominated by a mysterious fluid called dark energy which has absolutely no explanation from any fundamental theory of physics. And I'm here to argue that this dark energy does not in fact exist; that it is a figment of the astronomers' imagination. It has come about that they find a large value for this dark energy because they're interpreting the detail in an over-simplified model of the universe.

EH: So it sounds like you're coming in here as slightly the underdog, in the minority view. But what evidence do you have for something different existing than this concept of dark energy?

SS: There are various avenues that need to be explored further. For example, the effect of approximating the inhomogeneous universe in which we do find ourselves by the idealised homogeneous universe model, which is used to interpret the data. As to whether that is sufficient to account for the data without dark energy is a matter of ongoing study. We haven't come to a conclusion. And in fact the appeal of the dark energy model is that it is "simple", to astronomers at any rate. As to how precisely the complex universe when interpreted in this over simplified model gives a value for the dark energy, which is non-zero, is something that has yet to be demonstrated. But I'm convinced that it is the answer and that further observations will reveal it. And I just wish that astronomers would stop pursuing this kind of model and do the hard work of checking their approximations.

EH: So am I right in understanding that it's not that there's two competing theories it's that there's a sort of prevalent theory and you just think that it's incorrect and work needs to be done to find an alternative?

SS: Yes. Further distinction I think one should make here is between the theory and the model. What they have is a model not a theory. And the best way I can tell you the difference between them is actually I think something that Manfred Eigen said that theory must be either right or wrong. The model has a third ordinative: it might be right but irrelevant. So the question is, is this model relevant to the universe.

EH: Thank you very much. So many people are arriving for this debate here this afternoon that it's quite crowded in the little reception area here. And there's even people waiting on the off-chance that people aren't going to turn up, queuing to see if they can get a seat. Roberto, if I can just come back to you for a second. This is obviously one in a series of debates. What other topics are you going to be covering in the series.

Roberto Trotter: The next debate is goin g to be in September and that debate will tr y and ask another big qu estion which is whether other universes exist apart from our own. And I will be confronted with Professor Bernard Carr from Queen Mary University and we're going to debate whether it is a scientific question, first of all, whether different universes from our own exist and if so how can we possible tell in the future. And then we'll have another very interesting, very exciting, very topical debate in November: the future of space flight. So that's coming up in November and it's going to be very exciting and a very topical theme.

Gareth Mitchell: And if you'd like to book your place for that then check out the Astrophysics Group website at imper That was Roberto Trotter talking there to Elizabeth Hawk. And you can hear more of Elizabeth in action on the Short Science radio show and podcast that she co-hosts with fellow Science Media Production MSc student Georgie Gould. More details at

Well, finally, aviation. And as we'll all recall, June saw the tragic crash of an Air France airliner on route from Brazil to France. Whilst catastrophic for the loved ones of those killed, such disasters are thankfully rare. Aviation is stringently regulated and, for the most part, an incredibly safe form of transport. But Imperial is part of international efforts to make flying even safer.

In the Civil Engineering Department a group in the Centre for Transport Studies is involved in research to study in huge detail the complex mix of human, technical and natural factors that affect aviation. That involves pouring through masses of flight data to tease out little fragments of information that might have a bearing on safety. In fact one of the big difficulties is just how rare accidents actually are. They're so far and few between that it's often hard to draw statistically significant conclusions about risk factors. So part of the job is to find them within the far bigger collection of data where accidents haven't happened or where they've been avoided. So Arnab Majumdar, Lloyds Register Educational Trust Lecturer of Transport Risk Management, told me about some of the aspects of safety in the skies that go beyond just fastening your seatbelt.

Arnab Majumdar: The seatbelt on the passenger is one very visible form of aviation safety. But actually you can think of aviation safety as ensuring the passenger is safe, doesn't have injury or gets killed from the moment he or she boards the plane to the moment they disembark. And it's much more than just what goes on in the aircraft: the seatbelt, the engines being safe to how the pilots are. Are they tired? Have they been trained properly? To the air traffic control where the controllers safely separate the aircraft through the airspace through which they fly. All the way down to the actual airport surface itself with all the baggage handlers moving their trucks around at a big airport such as Heathrow where you've got so many complex movements going on on the ground. So safety, as I would understand it, is just to ensure that nothing happens to the passengers, the aircraft, from the moment the passenger gets on to the plane till when they get off.

GM: And it's only when you say that that I realise what a complex system this all is. So you have the pilot at the front of the plane. You have the air traffic controllers. And even things down to making sure you don't have debris on the runway. Because I immediately think, of course, of the tragic Concorde disaster and I think I'm right in saying that was down to some road debris on the runway that pierced the fuel tanks, wasn't it?

AM: Yes, that tragedy was down to that. And you find such untoward events happening all throughout the aviation system. In fact it's a testament to the great professionalism and skill with which all the human actors play their parts that we have so few accidents in the aviation system as a whole. It's very rare to have mid-air collisions. The role of the human cannot be underestimated. It is they who interact so closely with the system, whether it's from air traffic control or flying pilots or ensuring that even our baggage and trucks get handled properly. Understanding how the human operates in this complex system with equipment and procedures is really a key to aviation safety.

GM: And it's interesting how when we talk about the human factors in aviation quite often it's in a negative way. So when you have investigations of air crashes and disasters and it boils down to that awful phrase "pilot error". And it seems a lot of what you do here is looking at the positive side of things. The cases where maybe accidents were avoided because humans acted in a good way. I'm thinking about that incredible story of the American pilot that landed successfully on the Hudson River after losing both his engines. That's a really good example of human factors working in a positive way to save lives.

AM: Yes, and that's a very excellent example you've given there. I don't personally use the term human error very much. I use human performance, human reliability analysis. That's another way of looking at how humans interact with the system. You're right, humans are very positive. Not just the flight over the Hudson. Research here at the Centre for Transport Studies have looked at how air traffic controllers recover when the equipment fails and we find that communications and teamwork are such essential elements in a very successful recovery for air traffic controllers should the radar screen freeze and the position of aircraft be unknown to them.

GM: Let's speak also to your colleague who is also here, Mary Dominique Dupuiy, who is a research assistant also supported by the Lloyds Register Educational Trust. So, Mary, what's your work particularly involved with?

Mary Dupuiy: My work is to deal with safety measurement methods. So, basically, like you have a traditional way of measuring safety based on the number of accidents or what we call accident rates. But in aviation you have a very low accident rate so you have to focus your measurements towards other type of data. So other safety data and incidents where safety has been jeopardised but you don't have an outcome that results in an accident.

GM: I guess that your role then really is to come up with some kind of objective framework for looking at all this data. But the bigger picture here, I'd imagine, is that you're going back to the aviation industry, to air traffic controllers, pilots, airlines, airports and all these other stakeholders to give them pointers as how they can make aviation even safer.

MD: As our main objective is to improve safety, yes, we try to provide recommendations. And the type of recommendation that we might come up with are providing improvements to the collection process of the data. They might not collect the right thing or the information that would be useful for them. Or we might come up with a recommendation for the training aspect. How they can help the pilots or their traffic controllers to understand complex situations or to understand what are the precursors to potential incidents and accidents.

GM: Arnab, coming back to you, I guess when you sit on an aircraft yourself you know a lot more about this than us and your fellow passengers. How safe do you feel?

AM: I feel very safe. I put the shades over my eyes and rest. I have no reasons for worry. A few years ago I was on a flight where the aircraft tried to land but it couldn't break thunderstorms and the passengers next to me were quite frightened. But I explained to them, look, at the end of the day, the pilots have been well trained. The aircraft has been properly maintained according to regulations. You are in the best of hands here. The pilots, after two attempts, chose to go to another airport. They followed absolutely the regulations and the rules and acted perfectly within the safe way. And actually I sometimes take the chance to catch up on reading about incidents and accidents onboard flights so I don't worry. I don't worry because I think if you see the regulations, the very detailed procedures that must be followed before every flight. What goes on in the air traffic control room, and I've been very fortunate to see some of the busiest air traffic control centres in the world. So I have no worries. The people involved in the aviation industry actually are very well trained, very well regulated and tend to act with the passengers' safety as the foremost thing at all times.

GM: Arnab Majumdar and his colleague Mary Dominique Dupuiy bringing this month's podcast to an end. We'll have more for you in September, of course, including this:

Gordon Conway: I've been to nearly all the poorest neighbourhoods in the USA, Southside of Chicago, West Sacramento, south of Boston, Los Angeles, New Orleans and so on and one of the most delightful of the people was the Head of the Housing and Urban Development Department who we worked with who was a Jesuit priest. This was under Bill Clinton and Bill Clinton was quite happy to appoint a Jesuit priest as Head of his housing programme. And I had wonderful days bargaining with this Jesuit over how much money we were going to get out of government.

GM: Well, all that bargaining was about improving living conditions for some of American's poorest people. And in part two of my interview with international development professor Gordon Conway next time I'll be hearing about his role in everything from social housing in the United States to being the chief scientist in a major UK government department. Join me for that and much more from around Imperial.

This theme music is from Oscar Buldum and our podcast is jointly produced by Imperial's Press Office and the Science Communication Group. Thank you very much for listening and I'll see you next time. Bye-bye.